Speaker enclosure

ABSTRACT

A speaker enclosure for improving the frequency response of a loudspeaker. The speaker is placed within the enclosure and has its face aligned perpendicularly with the front side of the enclosure, so that the speaker axis is directed parallel to the sound output opening of the enclosure. The smallest dimension of the speaker face corresponds with the depth of the enclosure, and said speaker face is sealed against a baffle system which forms a channel directed divergingly outward from the speaker toward one end of the enclosure. A faceplate is sealed over the front of the enclosure and against the forward edge of the baffle system, said faceplate being provided with a cutout portion over the channel of the baffle system. The cutout portion is narrow at the face of the speaker, and becomes gradually wider toward the end of the enclosure to control the uniformity of the frequency response of the enclosure.

United, States Patent John A. McKenzie North Vernon, Ind. 865,415

Oct. I0. 1969 Jul 6, I97] Arvin Industries, Inc. Columbus, Ind.

Inventor Appl. No. Filed Patented Assignee remorse-res References CitedUNITED STATES PATENTS 1,210,411 8/1940 Beneckeetal..;

Gray

2,643,727 /1953 Leon................:::::::

Primary Examiner-Stephen J. Tomsky Attorney-Trask, Jenkins & HanleyABSTRACT: A speaker enclosure for improving the frequency response of aloudspeaker. The speaker is placed within the enclosure and has its facealigned perpendicularly with the front side of the enclosure, so'thatthe speaker axis is directed parallel to the sound output opening of theenclosure. The smallest dimension of the speaker face corresponds withthe depth of the enclosure, and said speaker face is sealed against abaffle system which forms a channel directed divergingly outward fromthe speaker toward one end of the enclosure. A faceplate is sealed overthe front of the enclosure and against the forward edge of the bafflesystem, said faceplate being provided with a cutout portion over thechannel of the baffle system. The cutout portion is narrow at the faceof the speaker, and becomes gradually wider toward the end of theenclosure to control the uniformity of the frequency response of theenclosure.

SPEAKER ENCLOSURE BACKGROUND OF THE INVENTION Speakers are availableover a wide price range depending primarily on their frequency responseand power output capabilities. Generally, an inexpensive speaker has arelatively poor frequency response and a low power output capability,and therefore is normally used only with small radios, phonographs, ortape recorders, where a large and more expensive speaker system is notdesirable. Thus, the sound reproduction ofa portable unit is normally ofinferior quality.

It is an object of this invention to provide a speaker enclosure whichrequires a relatively small volume, but which improves greatly thefrequency response of a small and inexpensive speaker as is commonlyused in portable sound devices.

SUMMARY OF THE INVENTION In accordance with the invention my speakerenclosure comprises a cabinet having a sound output opening in one side,and having a speaker mounted with its axis parallel to the plane of saidopening. The speaker is disposed at one end of the cabinet and has aplurality of baffles sealed against its output face and directed towardthe other end of the cabinet, said baffles-providing a channel divergingoutwardly from the face of the speaker. A faceplate fits over thechannel formed by the baffles, and it has an opening therein which formsthe sound output opening of the enclosure. The opening in the faceplateis somewhat horn shaped, beginning narrowly at the face of the speaker,and extending in a diverging manner outward toward the other end of thecabinet.

Preferably, the speaker has a rectangular face arranged with its minordimension corresponding to the depth of the cabinet, so that the depthdimension of the cabinet is about the same as the minor dimension of thespeaker. A rear baffle is sealed against the rearward major dimensionaledge of the speaker and extends toward the other end of the enclosurealong a gradually slanted line toward the front of the enclosure. Thisbaffle surface has a sharp transition near said other end of the cabinetand angles more sharply toward the sound opening face of the enclosure.A pair of side baffles are sealed against the minor dimensional edges ofthe speaker and slant outwardly toward the other end of the enclosure,until they reach said transition point where they turn outwardly toangle more sharply toward the corners of the cabinet at said other end.The faceplate is sealed against the forward edge of the speaker andagainst the forward edges of the side baffles so that there can be nointeraction between the air at the rear of the speaker and the air atits output face.

The opening in the faceplate of the device can be adjusted to tune theenclosure to provide a flat frequency response by placing notches orextensions in the wall of said opening. The narrow portion of thefaceplate opening, adjacent the output face of the speaker, isassociated with the high frequencies of the frequency response, whilethe broad outer portion of the opening is associated with the lowfrequency sounds generated by the speaker. Thus, any peaks or valleys inthe frequency response, from the high end to the low end, can besmoothed out by placing a notch or extension in the edge of thefaceplate corresponding to the frequency of that peak or valley.Similarly, the high or low end of the frequency response can beeffectively cut off by blocking the opening at its narrow or broadenedends.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing illustratesthe invention. In such drawing:

FIG. I is a front elevation ofa speaker enclosure embodying myinvention;

FIG. 2 is a front elevation of the enclosure shown in FIG. l but withthe faceplate removed therefrom; and

FIG. 3 is a vertical section taken along line 3-3 of FIG. I.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The enclosure, as shownin the drawing, is formed by a rectangular cabinet 10 having sidewalls14, end walls 12, and a backwall l6, and including a faceplate l8havingsound output openings 20 provided therein. The drawing shows twospeakers 22 and 24 housed in a single enclosure which is divided intosections by a partition 26 interconnected between the sidewalls 14 atthe center of the cabinet. It is to be understood, however, that where ahigh-power output is not required, a single speaker may be used,whereupon the partition 26 would comprise one of the end walls of thesingle speaker cabinet.

The interior of the enclosure is illustrated in FIG. 2 where thefaceplate 18 has been removed, and said interior holds a plurality ofbaffles which are placed in a particular configuration to affect thefrequency response of the speakers. As shown, the device is symmetricalabout the partition 26, and therefore only one-half of the enclosurewill be described. The speaker 24 may be a small inexpensive device suchas a 3X5 speaker commonly used in single speaker home entertainmentunits. Said speaker 24 is mounted with its axis parallel to the frontplate of the cabinet, and with its minor dimensional edges 27corresponding to the depth of the cabinet. Thus, the sound wavesgenerated by the speaker are directed toward the end panel 12 of thecabinet rather than directly outward as in other commonly knownenclosures. One portion of the baffle structure is formed by rearbaffles 28 and 30 and functions to direct the sound waves outwardly fromthe opening 20 in the faceplate 18. Therefore, the baffles 28 and 30 arearranged on a slant from back to front in the enclosure, starting at therear edge 31 of the speaker and terminating at the forward edge of theend of the enclosure. The baffle 28 extends at a gradual angle from saidrear edge of the speaker toward the end of the cabinet, while the baffle30 extends from the outer end 32 of baffle 28 and angles sharply towardthe faceplate of the enclosure, adjacent the end 12, thereby giving theeffect of directing the sound waves outwardly. Desirably, the twobaffles 28 and 30, together with their angular transition as shown at32, could be replaced by a single exponentially curved baffle (notshown) for performing this sound-directing function. The rear baffles 28and 30 are supported by braces 34 fixed to the rear side 16 of theenclosure; or, alternatively the cabinet may be molded or assembled sothat said rear baffles serve also as the backwall 16 of the device.

The baffle structure further comprises two pairs of side baffles, eachpair being formed by an inner section 36 and an outer section 38, andsaid pairs extending respectively from the minor edges 27 of the speaker24, diverging outward toward the end of the cabinet. The inner baffle 36in each pair extends at a lesser angle than the outer one 38 and isabout as long as the rear baffle 28. The second baffle 38 in each pairextends from the end 40 of the inner baffle to the end of the cabinet ata sharp angle toward the sides 14 thereof. Thus, the distance betweenthe pairs of baffles increases as said baffles extend toward the end ofthe cabinet; and, the baffles 28, 30, 36, and 38 combine to provide achannel extending from the face of the speaker toward the end of theenclosure, and becoming wider as it approaches the enclosure end. It hasbeen found preferable to make the outer end of the channel about twiceas wide as the major dimension of the speaker.

The forward edge 42 of the speaker is coplanar with the forward edges ofthe enclosure, and with the forward edges 44 of baffles 36 and 38, sothat when the faceplate 18 is applied to the enclosure it contacts allof these forward edges. A resilient gasket or bead of sealing compoundis applied to said forward edges of the baffles and speaker to form aseal between the front plate and the channel so that the air is isolatedbetween the front and rear of the speaker. Furthermore, the air at therear of the two speakers is divided and isolated by the panel 26, andair openings 46 are provided in the rear wall of the enclosure.

The openings 20 in the faceplate 18 are shaped to tune the frequencyresponse of the sound emitted from the channel. Each opening 20 beginsat the forward edge of the speaker with which it is associated, and thewalls of the opening project in parallel for a short distance from theface of the speaker as the opening extends toward the end of theenclosure. Said opening is narrow at its parallel portion adjacent theface of the speaker, and has a width equal to about one-third the majordimension of the speaker. The walls of the opening curve outwardly asthey extend toward the end of the enclosure, and then slant at an angletoward the corners of the enclosure to correspond with the edges of thebaffles 38. It has been found that high notes move a smaller amount ofair than do the bass notes generated by a speaker, and therefore thewidth of the ope ning-is small adjacent the speaker so that the high endof the frequency response can be controlled by widening or narrowing thewidth of the opening adjacent the speaker face. Accordingly, the widthof the opening is greater toward the end of the enclosure where the-bassnotes are more prominent and where a greater volume of air must bemoved. Similarly, the opening can be widened or narrowed at the end ofthe enclosure to trim the frequency response at its low end.

In summary, the speaker enclosure as described herein receives thespeaker on itsside to require a relatively small form factor whilepermitting a bafflesystem to operate on the sound output. The rearbaffles 28 and 30 and side baffles 36 and 38 cooperate with each otherto define a channel for directing the sound out the front of theenclosure. The

faceplate 18 seals over the channel forming an enclosed compartment,with the plate opening 20 extending over a portion of the channel in anexponentially diverging manner from the face of the speaker, and thenextending angularly toward the outer ends of the side baffles, tocontrol the frequency response curve of the enclosure.

lclaim:

l. A speaker enclosure, comprising a housing having an open front face;a speaker mounted in said housing and having its output face directedperpendicularly to said front face; baffle means open'to said front faceand extending laterally and forwardly outwardly from the output face ofthe speaker toward said front face; and a faceplate covering said frontface of said housing and abutting said baffle means to form an enclosedcompartment with said baffle means and speaker output face, saidfaceplate having an opening therein disposed over said compartment; saidfaceplate opening diverging laterally outwardly from the speaker outputface for controlling the frequency response of said compartment.

2. The invention as set forth in claim 1 in which said baffle meansextend divergingly away from the sides of the speaker output face.

3. The invention as set forth in claim 1 with the addition that a secondspeaker is mounted in said enclosure with the rear sides of saidspeakers lying adjacent each other and their output faces directed inopposite directions; second baffle means open to said front face andextending laterally and forwardly outwardly from the output face of thesecond speaker toward v said front face; said faceplate forms a secondenclosed compartment with said second baffle means and second speakeroutput face; and said faceplate has a second opening therein disposedover said second compartment and diverging laterally outwardly from saidsecond speaker output face for controlling the frequency response curveof said second compartment. Y

4. A speaker enclosure, comprising a housing having an open front face;a speaker mounted in said housing and having its output face directedperpendicularly to said front face; a rear baffle extending from thespeaker output face at the rear of the housing toward the front face ofthe housing and away from the speaker output face; a pair of sidebaffles extending respectively along the sides of said rear baffle andeach extending from the sides of the speaker and from front to rear inthe housing; said side and rear baffles forming a channel incommunication with, and extending away from, the output face of thespeaker; and a faceplate covering said front side of said housing andhaving an opening therein disposed over said channel; said faceplateopening diverging laterally outwardly from the speaker output face forcontrolling the frequency response curve of said channel.

5. The invention as set forth in claim 4 in which said side bafflesdiverge laterally outwardly from said output face toward the end of saidchannel remote from the speaker.

6. The invention as set forth in claim 5 in which said faceplate openingis narrower than said channel at the speaker output face with thelateral edges of said opening extending laterally from said speakeroutput face toward the sides of the channel in an exponential manner,and then angling further laterally outward adjacent the outer end of thechannel.

7. The invention as set forth in claim 6 with the addition that saidfaceplate opening is narrower than said channel at the speaker outputface with the lateral edges of said opening extending laterally fromsaid speaker output face toward the sides of the channel in anexponential manner, and then angling laterally outwardly adjacent theouter end of the channel, said side baffles diverging laterally fromsaid output face toward the outer end of said channel, the angle atwhich said side baffles and said rear baffle extend from said outputface becoming more obtuse at a common plane adjacent the end of theenclosure remote from the speaker.

8. The invention as set forth in claim 4, with the addition that asecond speaker is mounted in said enclosure with the rear sides of saidspeakers lying adjacent each other and their output faces directed inopposite directions; a second rear baffle extends from the secondspeaker face at the rear of the housing toward said housing front face;a second pair of side baffles extends respectively along the sides ofsaid second rear baffle from said rear baffle to said housing frontface; said second side and rear baffles forming a second channel incommunication with the output face of the second speaker; and saidfaceplate covers said second channel and has a second opening thereindisposed over said second channel and diverging laterally outwardly fromsaid second speaker output face for controlling the frequency responsecurve of said second channel.

1. A speaker enclosure, comprising a housing having an open front face;a speaker mounted in said housing and having its output face directedperpendicularly to said front face; baffle means open to said front faceand extending laterally and forwardly outwardly from the output face ofthe speaker toward said front face; and a faceplate covering said frontface of said housing and abutting said baffle means to form an enclosedcompartment with said baffle means and speaker outPut face, saidfaceplate having an opening therein disposed over said compartment; saidfaceplate opening diverging laterally outwardly from the speaker outputface for controlling the frequency response of said compartment.
 2. Theinvention as set forth in claim 1 in which said baffle means extenddivergingly away from the sides of the speaker output face.
 3. Theinvention as set forth in claim 1 with the addition that a secondspeaker is mounted in said enclosure with the rear sides of saidspeakers lying adjacent each other and their output faces directed inopposite directions; second baffle means open to said front face andextending laterally and forwardly outwardly from the output face of thesecond speaker toward said front face; said faceplate forms a secondenclosed compartment with said second baffle means and second speakeroutput face; and said faceplate has a second opening therein disposedover said second compartment and diverging laterally outwardly from saidsecond speaker output face for controlling the frequency response curveof said second compartment.
 4. A speaker enclosure, comprising a housinghaving an open front face; a speaker mounted in said housing and havingits output face directed perpendicularly to said front face; a rearbaffle extending from the speaker output face at the rear of the housingtoward the front face of the housing and away from the speaker outputface; a pair of side baffles extending respectively along the sides ofsaid rear baffle and each extending from the sides of the speaker andfrom front to rear in the housing; said side and rear baffles forming achannel in communication with, and extending away from, the output faceof the speaker; and a faceplate covering said front side of said housingand having an opening therein disposed over said channel; said faceplateopening diverging laterally outwardly from the speaker output face forcontrolling the frequency response curve of said channel.
 5. Theinvention as set forth in claim 4 in which said side baffles divergelaterally outwardly from said output face toward the end of said channelremote from the speaker.
 6. The invention as set forth in claim 5 inwhich said faceplate opening is narrower than said channel at thespeaker output face with the lateral edges of said opening extendinglaterally from said speaker output face toward the sides of the channelin an exponential manner, and then angling further laterally outwardadjacent the outer end of the channel.
 7. The invention as set forth inclaim 6 with the addition that said faceplate opening is narrower thansaid channel at the speaker output face with the lateral edges of saidopening extending laterally from said speaker output face toward thesides of the channel in an exponential manner, and then anglinglaterally outwardly adjacent the outer end of the channel, said sidebaffles diverging laterally from said output face toward the outer endof said channel, the angle at which said side baffles and said rearbaffle extend from said output face becoming more obtuse at a commonplane adjacent the end of the enclosure remote from the speaker.
 8. Theinvention as set forth in claim 4, with the addition that a secondspeaker is mounted in said enclosure with the rear sides of saidspeakers lying adjacent each other and their output faces directed inopposite directions; a second rear baffle extends from the secondspeaker face at the rear of the housing toward said housing front face;a second pair of side baffles extends respectively along the sides ofsaid second rear baffle from said rear baffle to said housing frontface; said second side and rear baffles forming a second channel incommunication with the output face of the second speaker; and saidfaceplate covers said second channel and has a second opening thereindisposed over said second channel and diverging laterally outwardly fromsaid second speaker output face for controlling the frequency responsecurve of said second chanNel.